The invention relates to a cooktop having a glass or glass-ceramic plate defining a cooking surface and at least one cook location which is heated by a gas burner.
Cooktops or ranges having a glass/glass-ceramic plate defining a cook surface and cook locations, which are heated by respective gas burners, have been successfully in the marketplace for many years.
With respect to gas burners, one can distinguish between basically two burner systems:
a) The gas radiation burner, which is mounted below the glass/glass-ceramic plate and whose energy is imparted via radiation to the pot base in a manner similar to the known electric heating element. This burner is a so-called premix burner, that is, all air required for combustion is mixed with the gas in a mixture chamber and combusted at the top side of the burner medium. No additional combustion air (that is, no secondary air) is required on the flame end.
b) The conventional atmospheric gas burner as used for so many years in household ranges. In this type of burner, a part of the combustion air is drawn in by suction with the combustion gas via a venturi nozzle and mixed. However, for a good and complete combustion of the supplied gases, a supply of additional combustion air, the secondary air, is required for the combustion.
The operation and the control performance of both burner systems is different because of the function principle. The radiation burner can be clocked on and off at different time intervals and can thereby be controlled very finely. The atmospheric gas burner is controlled via the quantity of the added gas which usually takes place via the adjustment of the gas valve.
Both burner systems are used in the marketplace even though both systems are still burdened with disadvantages. The radiation burner in the form known today (for example, from German patent publication 197 03 301) is mounted below the closed planar glass/glass-ceramic cooking surface. This means that the hot combustion gas cannot reach the cooking utensil as in the normal atmospheric gas burner; instead, the combustion gas must be conducted away via separate channels from the cooktop. This exhaust-gas guidance requires a high constructive complexity and takes up a considerable amount of space in the cooktop which leads to a substantial limiting of the configuration possibilities. In these radiation burners, the combusted hot exhaust gas cannot be supplied to the actual cooking process. For this reason, the utilization of energy of the cook location is greatly reduced. This defect does not occur in an atmospheric gas burner having an open gas flame as described, for example, in German patent publication 198 13 691. In this type of burner, substantially the largest portion of energy transfer to what is being cooked takes place via the hot exhaust gas. As a significant disadvantage in this burner system, it has been shown in practice that a pot support has to be used over the gas burner to ensure an adequate combustion and to provide a reliable stand for the cooking utensil. This pot carrier is, on the one hand, very expensive with respect to its manufacture and, on the other hand, is burdened with tolerances with respect to centering and configuration and these tolerances can greatly affect the function and support reliability of the cooking utensil. Four pot carriers must be used when utilizing conventionally four burner locations whereby the problem is significantly increased.
It is an object of the invention to configure the cooktop mentioned initially herein with a glass or glass-ceramic plate as a cooking surface and at least one cook location which is heated by a gas burner so that it is not necessary to configure complex exhaust-gas channels in the case of using gas radiation burners and the exhaust gas can be utilized for heating the cooking utensils or, in the case of atmospheric gas burners, separate pot supports are unnecessary.
The solution of this task is achieved starting from a cooktop having a glass or glass-ceramic plate as a cooking surface and at least one cook location which is heated by a gas burner. This solution is achieved in accordance with the invention in that the burner location is formed by a mesa-like protrusion in the glass or glass-ceramic plate and the gas burner is mounted below this protrusion. The mesa-like surface is the pot position surface and is formed with a peripheral flank in which openings are formed.
In the cooktop according to the invention, the exhaust gases can exit through the openings in the flank in the case of gas radiation burners and can be used additionally to heat cooking utensils placed thereon. No constructively complex exhaust-gas channels transversely across the cooktop are required.
In the case of atmospheric gas burners, the protrusion can be used directly as a pot support. Depending upon the configuration of the gas burner, the openings in the flank can function as passthrough openings for flames or a mixture to be combusted.
International patent publication WO 97/47 927 A1 discloses a gas cooktop having different cook surface levels; however, the known gas cooktop has basically another basic configuration than the cooktop of the invention. It does, in principle, likewise have a glass-ceramic plate as a cooking surface and four cook locations (burner locations) which are heated by respective gas burner positions; however, the configuration of the gas burner positions is basically different than in the case of the invention.
According to the invention, the gas burner locations are each formed by a mesa-like protrusion in the cooking surface plate below which typically a complete (conventional) gas burner is mounted having a burner head including a burner crown and a cover in the case of atmospheric gas burners or a complete gas radiation burner. In the case of four burner locations, a gas burner is assigned to each protrusion, that is, four protrusions and four gas burners are provided. The protrusion surrounds the gas burner with the mesa surface as a pot placement surface and the surrounding flank or the openings formed therein for the exit of the flame or exhaust gas.
In the case of the known gas cooktop, the burner locations are not formed by protrusions in the glass-ceramic plate but by depressions. Also, there is no complete gas burner assigned to the gas burner locations, which would especially heat a pot placement surface; instead, the pot stands between a central area and respective corner areas which are separated by the recesses. Flame openings are formed in the flanks of the opposite-lying recesses. These flame openings are fired by means of a central gas supply (not shown) below the corner areas. The central gas supply in combination with a suitable configuration of the flame openings should allow a desired improved controllability of the gas burner locations. A central gas burner location below the central location could not achieve the desired firing of the gas burner locations.
In accordance with a first embodiment of the invention, the protrusion is configured as a truncated cone. Such a protrusion can be made with simple forming means.
To increase the pot placement surface of the protrusion, it is practical according to a further embodiment of the invention, to configure the protrusion as star-shaped with the three or more stars at an oval or circular base surface. This configuration relates to the star-shaped configuration of the mesa-like shaped protrusion of the cook surface f or directly forming the pot support; in contrast, WO 99/20942 A1 shows only a star-shaped burner head of an atmospheric gas burner to which a conventional pot support is assigned which therefore is not to be replaced.
The openings in the peripherally extending flank can be configured as slots or as circular-round openings depending on the type of gas burner used. Other forms are also conceivable, for example, oval or star-shaped openings. Slots or circular-round holes are, however, simple to form.
According to a further embodiment of the invention, the cooktop is so configured that a conventional gas radiation burner having a mixture chamber and burner medium is mounted below the protrusion and the base surface of the protrusion is so selected that the gas radiation burner can be seal-tight attached along the periphery of the base surface via an insulation ring. The hot exhaust gases, which arise in the space above the burner medium, exit through the openings in the peripherally extending flank and reach the placed cooking utensil without it requiring extensive exhaust-gas channels. This leads to a reduction of the precooking time and to a more efficient utilization of energy.
According to another embodiment of the invention, the cooktop is so configured that a conventional atmospheric gas burner is mounted below the protrusion and the base surface of the protrusion is so selected that the flames of the atmospheric gas burner burn exclusively within the protrusion.
In this way, a separate pot support is unnecessary as required in conventional burner locations having atmospheric gas burners.
In a further embodiment of the invention, the cooktop is so configured that an atmospheric gas burner having an adapted burner crown in mounted below the protrusion and the base surface of the protrusion is so selected that the burner crown of the gas burner with its crown bores is so aligned with openings in the peripherally extending flank against the inner side of the flank that the flames of the atmospheric gas burner burn through the openings. In this way, the flames of the atmospheric burner reach directly to the placed utensil.
In an extension of this concept, and according to a further embodiment of the invention, the cooktop is so configured that an atmospheric gas burner without a burner crown having gas passthrough openings is mounted in the burner head below the protrusion and the protrusion is so configured that the burner head lies so tightly against the inner side of the peripherally extending flank that the air/gas mixture of the atmospheric gas burner passes through the openings in the peripherally extending flank and combusts outside of the flank.
In an embodiment of this kind, the bores in the peripherally extending flank or this flank region assume the function of the burner crown whereby the atmospheric gas burner can be configured of fewer components.
According to another embodiment of the invention, the cooktop is so configured that the openings are so formed in the peripherally extending flank that their longitudinal axes are perpendicular to the flank surface. In an embodiment of this kind, the openings can be formed already in the planar state of the glass or glass-ceramic plate in advance of forming the partial protrusion.
Excellent peripheral protection is given when the openings are so formed in the peripherally extending flank that their longitudinal axes extend parallel to the cook surface formed by the glass or glass-ceramic plate.